GR IR posing reference PO

Dear friends,

I would like to understand the GR/IR posting for below transaction

Item A    with standard cost of 799.35/1000

               Qty          PO price              total amount

PO        59976         730/39996           43782.48

IR          39996                                   43782.48

GR        59976                                   43782.48

My GR accounting posing is like below

Dr. Inv          47941.82

Cr. GR/IR     58367.88

PPV            10426.06

my question is : how did the amount 58367.88 being formed.

from what I understanding it should be 65654   (43782.48/39996*59976)

my assumption is it's caused by some soft of tolerance. if i m right, where should it be cofigured.. otherwise, what makes the number.

thanks in advance,

Linda